A Canvas for Thought

July 13, 2007

Setting a custom Ruby GEM_HOME on Ubuntu Feisty

Filed under: Uncategorized — vednis @ 1:23 pm

Here is a quick and painless solution for setting your own Ruby GEM_HOME in Ubuntu Feisty.

First, I’ll assume that you have installed the ruby and rubygems packages, and set your new GEM_HOME:

$ sudo apt-get install ruby rubygems
$ mkdir -p /home/mars/lib/ruby/gems
$ export GEM_HOME=/home/mars/lib/ruby/gems

All looks well, until we try to install something with the ‘gem’ command:

mars@sol:~/tmp$ gem install rake
/usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require': no such file to load -- sources (LoadError)
    from /usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `require'
    from /usr/lib/ruby/1.8/rubygems/remote_installer.rb:462:in `sources'
    from /usr/lib/ruby/1.8/rubygems/remote_installer.rb:472:in `source_index_hash'
    from /usr/lib/ruby/1.8/rubygems/remote_installer.rb:436:in `install'
    from /usr/lib/ruby/1.8/rubygems/gem_commands.rb:263:in `execute'
    from /usr/lib/ruby/1.8/rubygems/gem_commands.rb:225:in `each'
    from /usr/lib/ruby/1.8/rubygems/gem_commands.rb:225:in `execute'
    from /usr/lib/ruby/1.8/rubygems/command.rb:69:in `invoke'
    from /usr/lib/ruby/1.8/rubygems/cmd_manager.rb:117:in `process_args'
    from /usr/lib/ruby/1.8/rubygems/cmd_manager.rb:88:in `run'
    from /usr/lib/ruby/1.8/rubygems/gem_runner.rb:28:in `run'
    from /usr/bin/gem:23

Oops.  We are missing a file called ‘sources.rb’.  That file, curiously enough, is contained in the ‘sources’ gem.

So, we try this:

mars@sol:~/tmp$ gem install sources
/usr/lib/ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require': no such file to load -- sources (LoadError)

Same error. Drat!

Thankfully, there is a simple solution.  The sources gem was installed in feisty’s default gem cache:

mars@sol:~/tmp$ locate sources.rb

mars@sol:~/tmp$ ls /var/lib/gems/1.8/cache/

We can install the original gem into our new GEM_HOME.  Just make sure that you pass the ‘–local’ switch to the gem command, so that it doesn’t check for remote sources!

mars@sol:~/tmp$ gem install --local /var/lib/gems/1.8/gems/cache/sources-0.0.1.gem
Successfully installed sources, version 0.0.1

Now everything works as expected; we can install gems without using sudo:

mars@sol:~/tmp$ gem install rake
Bulk updating Gem source index for: http://gems.rubyforge.org
Successfully installed rake-0.7.3

P.S. Don’t forget to set your PATH!

$ export PATH=$GEM_HOME/bin:$PATH

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  1. I was having this problem on my mac, and found your page via Google. hanks for taking the time to post this – you saved me!

    Comment by D — February 26, 2008 @ 10:54 am

  2. Errr…I mean “thanks for taking the time to post this”….it’s too early in the morning…

    Comment by D — February 26, 2008 @ 10:55 am

  3. This is great! I don’t have root at my work machine/ work cluster so I manage my own gem repo (getting IT to do it is like pulling teeth) and I’d run into this problem from time to time. I had to make sure paths were pointing to system-intalled stuff first or do some trickery with absolute paths (my gems more current than system ones). This makes that problem go away. Brilliant!

    side rant: it irritates me to no end that all installations assume everyone has root.

    Comment by mikshir — May 23, 2008 @ 9:47 am

  4. I found even simpler way here: http://ronallo.wordpress.com/2007/11/20/rubygems-without-sources-gem/

    Comment by emmek — May 13, 2009 @ 10:23 am

  5. Old article by now, but for those still coming across it… Taking a custom GEM_HOME a step further, I needed to build/test many apps in isolated gem environments, and I found myself longing for something like Python’s virtualenv. Turns out, Jacob Radford done did that:


    See the README on GitHub, but basically sandbox helps you create multiple gem environments and generates shell scripts for each one that you can source to set and unset GEM_HOME, GEM_PATH, etc.

    Comment by Ches Martin — October 25, 2009 @ 12:23 pm

  6. Although I guess rip is really the new hotness for that purpose :-)

    Comment by Ches Martin — October 25, 2009 @ 12:52 pm

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